This invention is directed to a transducer for an electronic timepiece and, in particular, to a step motor for use in a quartz crystal electronic timepiece.
Two particular areas of emphasis that have dominated the development of electronic analog display timepieces, and in particular wristwatches, are the improvement of the timekeeping accuracy of the timepiece and a reduction in energy consumption of the timepiece. By utilizing high frequency quartz crystal vibrators as a time standard, the accuracy of the time kept by the electronic timepiece has been dramatically improved. Similarly, efforts have been made to reduce power consumption, so that the life of the battery can be extended in an electronic wristwatch and thereby reduce the frequency with which the battery needs to be replaced.
It is noted, however, that in electronic timepieces having an electro-mechanical transducer mechanism, such as a step motor, the power consumption of the transducer mechanism is considerable when compared with the power consumption of the remaining components of the electronic circuit, such as the oscillator circuit, divider circuit, etc. Accordingly, a lowering of the power consumption of the electro-mechanical transducer will substantially increase the life of the battery.
It is also noted that efforts have been made to improve electro-mechanical transducers in electronic timepieces by maximizing the torque generated thereby without providing an attendant increase in current consumption. An electro-mechanical transducer arrangement for achieving this type of result in an electronic wristwatch is detailed in U.S. Pat. No. 3,984,972, which patent is assigned to the same assignee herein. It is noted, however, that electro-mechanical transducer arrangements of the type set forth in U.S. Pat. No. 3,984,972, although providing a suitable increase in torque without an increase in current consumption and, hence, improved efficiency, have been unable to effect a reduction in the current consumption of the transducer to a level that would effect a substantial increase in the life of the battery utilized to drive the electronic timepiece.